Beginning his epic study in the 1840s with Charles Baudelaire, whose lurid poetry scandalized French stalwarts, Peter Gay traces the revolutionary path of modernism from its Parisian origins to its emergence as the dominant cultural movement in world capitals such as Berlin and New York. Modernism is a sweeping, illustrated chronicle of rebellious creativity, from Oscar Wilde, Pablo Picasso, Walter Gropius, and D.W. Griffiths to James Joyce, Virginia Woolf, Arnold Schoenberg, and Marcel Duchamp. Gay also considers the hostility of totalitarian regimes to the subversiveness of modernism and the role of Pop Art in outdoing modernism's iconoclastic impulses.

"Now in his mid-80s, Yale professor Peter Gay has been one of our chief chroniclers of "the modern" for more than 50 years.... What is modernism? For Gay, the modernists shared two defining attributes: 'first, the lure of heresy that impelled their actions as they confronted conventional sensibilities; and, second, a commitment to a principled self-scrutiny.'... At its best, Modernism conveys the almost superhuman creative energies at large in the early and mid-20th century. Gay sees Picasso, Joyce, Stravinsky and Balanchine as the greatest masters of, respectively, image, word, sound and movement. But Marcel Duchamp—who once exhibited a urinal and labeled it Fountain—may be even more significant as a visionary: He is modernism's key subversive, undercutting everything we once believed about creativity and beauty, and consequently pioneering the more extreme forms of artistic expression. It is only a baby step from Duchamp's mustachioed Mona Lisa to Andres Serrano's Piss Christ. Like a good comparatist, Gay casts a wide net, covering Northern masters such as the Scandinavians August Strindberg and Edvard Munch, along with less familiar figures, such as the Russian Vladimir Tatlin and the German Georg Kaiser. He notes, too, that modernists come in every political stripe—the arch-conservative T.S. Eliot, the elitist Schoenberg, the anarchist-yippie Alfred Jarry, the Confederate nostalgist D.W. Griffith, the Marxist Sartre. Many important innovators were Jewish (Kafka, Walter Gropius, Proust, et al.), and Gay writes at length about the effects of the regimes of Hitler and Stalin on the arts. In many instances, the United States proved the beneficiary—émigré Jewish scholars re-energized our universities, the composers Stravinsky and Schoenberg ended up virtual neighbors in Los Angeles.... All such histories matter only if they send us off—for the first or 100th time—to listen to the pounding rhythms of The Rite of Spring, to hold our breath before Brancusi's delicate Bird in Space, to read To the Lighthouse or to visit Frank Lloyd Wright's Fallingwater. It is because of such imperishable works that modernism still matters—and always will."